I want to protect copyright of my photographs. So, I've decided I'd like to put some signature like information in my photos.
According to my research, - I have copyright as default and I don't need to do anything according to most countries' laws. - There are online services where I can register my photos. - And of course I can put watermarks on photos
The watermark option isn't a solution for me because my photos will be printed in books. So I need to share my raw photos with the publisher's partner company whom I don't trust.
The tricky part of my question start here; The paranoiac side of me says that they can steal and use my photos, say on the web, with out my permissions.
Anyway, I thought that if I could put some information (i.e. signature-like specific key) in my photo meta data or pixels (not sure this is possible) which can't be deleted later (better if it's not detectable by others) and I can trace/find my photos with search engines easily.
Is there any way to put such information in to achieve my goal ? Or are there any other methods for this purpose ?